Apple Inc.'s Chief Financial Officer Peter Oppenheimer will retire and hand the reins to Luca Maestri in September, entrusting to the Italian-born executive a cash pile the size of Vietnam's economy and the difficult task of guiding Wall Street's expectations.

The 50-year-old born in Rome is taking over with Apple at a crossroads. Investors continue to clamor for the company to put its industry-leading $160 billion hoard to better use than just parked overseas, while rivals Google and Facebook shell out tens of billions of dollars snapping up cutting-edge tech companies like Nest and WhatsApp.

Managing investors' outsized expectations may become more difficult as Apple - facing slowing revenue growth and more aggressive competition - dives deeper into lower-margin but higher-growth emerging markets like China, where cheaper local players Huawei and Xiaomi dominate.

"Maestri will be assuming this role at an interesting time - when Apple is in the midst of launching more services and likely needs to convince investors that it has more consistent revenue streams in a commoditizing smart phone market," Barclays analyst Ben Reitzes wrote on Tuesday.

"We know Maestri quite well and believe he will support consistent plans for capital return and thoughtful, achievable guidance."

Maestri, who has worked in countries from Brazil to Thailand, is not expected to pursue radical changes to the iPhone maker's capital return strategy.

Longer-term, the company is also under increasing pressure to come up with the next big thing. Some investors bet that Chief Executive Officer Tim Cook will finally unveil a revolutionary new product this year, breaking a dry spell of several years during which it stuck mainly to iterations of the iPhone and iPad.

Oppenheimer, 51, had been CFO since 2004 and was the architect behind a $100 billion capital return program established a year ago in response to demands the company do more with its ballooning cash hoard.

He joined Apple from Xerox Corp in 2013. He spent 20 years at General Motors where he worked as CFO of several units including GM Europe. Before joining Xerox, he was CFO of network equipment maker Nokia Siemens Networks.

TAKING UP THE BATON

Over the past few quarters, Oppenheimer has moved Apple, which for years routinely smashed investors' expectations, toward more realistic financial targets and outlooks as the company amassed size and expanded into new markets.

Its business has also grown rapidly beyond mainly hardware sales and into areas such as software and digital content. Now, Maestri assumes responsibility for